This application is related to subject matter disclosed in:                A1) U.S. provisional Application No. 60/111,484 entitled “An all-fiber-optic modulator” filed Dec. 7, 1998 in the names of Kerry J. Vahala and Amnon Yariv, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A2) U.S. Application No. 09/454,719, now U.S. Pat. No. 6,633,696 entitled “Resonant optical wave power control devices and methods” filed Dec. 7, 1999 in the names of Kerry J. Vahala and Amnon Yariv, said application being hereby incorporated by reference in its entirety as if fully set forth herein;        A3) U.S. provisional Application No.60/108,358 entitled “Dual tapered fiber-microsphere coupler” filed Nov. 13, 1998 in the names of Kerry J. Vahala and Ming Cai, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A4) U.S. Application No.09/440,311, now U.S. Pat. No. 6,580,851 entitled “Resonator fiber bi-directional coupler” filed Nov. 12, 1999 in the names of Kerry J. Vahala, Ming Cai, and Guido Hunziker, said application being hereby incorporated by reference in its entirety as if fully set forth herein;        A5) U.S. provisional Application No.60/183,499 entitled “Resonant optical power control devices and methods of fabrication thereof” filed Feb. 17, 2000 in the names of Peter C. Sercel and Kerry J. Vahala, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A6) U.S. provisional Application No.60/226,147 entitled “Fiber-optic waveguides for evanescent optical coupling and methods of fabrication and use thereof”, filed Aug. 18, 2000 in the names of Peter C. Sercel, Guido Hunziker, and Robert B. Lee, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A7) U.S. provisional Application No. 60/170,074 entitled “Optical routing/switching based on control of waveguide-ring resonator coupling”, filed Dec. 9, 1999 in the name of Amnon Yariv, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A8) U.S. Pat. No. 6,052,495 entitled “Resonator modulators and wavelength routing switches” issued Apr. 18, 2000 in the names of Brent E. Little, James S. Foresi, and Hermann A. Haus, said patent being hereby incorporated by reference in its entirety as if fully set forth herein;        A9) U.S. Pat. No. 6,101,300 entitled “High efficiency channel drop filter with absorption induced on/off switching and modulation” issued Aug. 8, 2000 in the names of Shanhui Fan, Pierre R. Villeneuve, John D. Joannopoulos, Brent E. Little, and Hermann A. Haus, said patent being hereby incorporated by reference in its entirety as if fully set forth herein;        Ab 10) U.S. Pat. No.5,926,496 entitled “Semiconductor micro-resonator device” issued Jul. 20, 1999 in the names of Seng-Tiong Ho and Deanna Rafizadeh, said patent being hereby incorporated by reference in its entirety as if fully set forth herein;        A11) U.S. Pat. No.6,009,115 entitled “Semiconductor micro-resonator device” issued Dec. 28, 1999 in the name of Seng-Tiong Ho, said patent being hereby incorporated by reference in its entirety as if fully set forth herein;        A12) U.S. provisional Application No.60/257,218 entitled“Wave guides and resonators for integrated optical devices and methods of fabrication and use thereof”, filed Dec. 21, 2000 in the name of Oskar J. Painter, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A13) U.S. provisional Application No.60/257,248 entitled “Modulators for resonant optical power control devices and methods of fabrication and use thereof”, filed Dec. 21, 2000 in the names of Oskar J. Painter, Kerry J. Vahala, Peter C. Sercel, and Guido Hunziker, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A14) U.S. provisional Application No.60/301,519 entitled “Waveguide-fiber Mach-Zender interferometer and methods of fabrication and use thereof”, filed Jun. 27, 2001 in the names of Oskar J. Painter, David W. Vernooy, and Kerry J. Vahala, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A15) U.S. non-provisional Application No.09/788,303 entitled “Cylindrical processing of optical media”, filed Feb. 16, 2001 in the names of Peter C. Sercel, Kerry J. Vahala, David W. Vernooy, and Guido Hunziker, said non-provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A16) U.S. non-provisional Application No.09/788,331 entitled “Fiber-ring optical resonators”, filed Feb. 16, 2001 in the names of Peter C. Sercel, Kerry J. Vahala, David W. Vernooy, Guido Hunziker, and Robert B. Lee, said non-provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A17) U.S. non-provisional Application No.09/788,300 entitled “Resonant optical filters”, filed Feb. 16, 2001 in the names of Kerry J. Vahala, Peter C. Sercel, David W. Vernooy, Oskar J. Painter, and Guido Hunziker, said non-provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A18) U.S. non-provisional Application No.09/788,301 entitled “Resonant optical power control device assemblies”, filed Feb. 16, 2001 in the names of Peter C. Sercel, Kerry J. Vahala, David W. Vernooy, Guido Hunziker, Robert B. Lee, and Oskar J. Painter, said non-provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A19) U.S. provisional Application No. 60/333,236 entitled “Alignment apparatus and methods for transverse optical coupling”, Docket No. CQC16P, filed Nov. 23, 2001 in the names of Charles I. Grosjean, Guido Hunziker, Paul M. Bridger, and Oskar J. Painter, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A20) U.S. non-provisional Application No. 10/037,966, filed Dec. 21, 2001 entitled “Multi-layer dispersion-engineered waveguides and resonators”, Docket No. CQC14NP, filed concurrently with the present application in the names of Oskar J. Painter, David W. Vernooy, and Kerry J. Vahala, said non-provisional application being hereby incorporated by reference in its entirety as if fully set forth herein.        
This application is also related to subject matter disclosed in the following publications, each of said publications being hereby incorporated by reference in its entirety as if fully set forth herein:                P1) Ming Cai, Guido Hunziker, and Kerry Vahala, “Fiber-optic add-drop device based on a silica microsphere whispering gallery mode system”, IEEE Photonics Technology Letters Vol. 11 686 (1999);        P2) J. C. Knight, G. Cheung, F. Jacques, and T. A. Birks, “Phased-matched excitation of whispering gallery-mode resonances by a fiber taper”, Optics Letters Vol. 22 1129 (1997);        P3) R. D. Pechstedt, P. St. J. Russell, T. A. Birks, and F. D. Lloyd-Lucas, “Selective coupling of fiber modes with use of surface-guided Bloch modes supported by dielctric multilayer stacks”, J. Opt. Soc. Am. A Vol. 12(12) 2655 (1995);        P4) R. D. Pechstedt, P. St. J. Russell, “Narrow-band in-line fiber filter using surface-guided Bloch modes supported by dielectric multilayer stacks”, J. Lightwave Tech. Vol. 14(6) 1541 (1996);        P5) Hiroshi Wada, Takeshi Kamijoh, and Yoh Ogawa, “Direct bonding of InP to different materials for optical devices”, Proceedings of the third international symposium on semiconductor wafer bonding: Physics and applications, Electrochemical Society Proceedings, Princeton N.J., Vol. 95-7, 579-591 (1995);        P6) R. H. Horng, D. S. Wuu, S. C. Wei, M. F. Huang, K. H. Chang, P. H. Liu, and K. C. Lin, “AlGaInP/AuBe/glass light emitting diodes fabricated by wafer-bonding technology”, Appl. Phys. Letts. Vol. 75(2) 154 (1999);        P7) Y. Shi, C. Zheng, H. Zhang, J. H. Bechtel, L. R. Dalton, B. B. Robinson, W. Steier, “Low (sub-1-volt) halfwave voltage polymeric electro-optic modulators achieved by controlling chromophore shape”, Science Vol. 288, 119 (2000);        P8) E. L. Wooten, K. M. Kissa, and A. Yi-Yan, “A review of lithium niobate modulators for fiber-optic communications systems”, IEEE J. Selected Topics in Quantum Electronics, Vol. 6(1), 69 (2000);        P9) D. L. Huffaker, H. Deng, Q. Deng, and D. G. Deppe, “Ring and stripe oxide-confined vertical-cavity surface-emitting lasers”, Appl. Phys. Lett., Vol. 69(23), 3477 (1996);        P10) Serpenguzel, S. Arnold, and G. Griffel, “Excitation of resonances of microspheres on an optical fiber”, Opt. Lett. Vol. 20, 654 (1995);        P11) F. Treussart, N. Dubreil, J. C. Knight, V. Sandoghar, J. Hare, V. Lefevre-Seguin, J. M. Raimond, and S. Haroche, “Microlasers based on silica microspheres”, Ann. Telecommun. Vol. 52, 557 (1997);        P12) M. L. Gorodetsky, A. A. Savchenkov, V. S. Ilchenko, “Ultimate Q of optical microsphere resonators”, Optics Letters, Vol. 21, 453 (1996);        P13) Carl Arft, Diego R. Yankelovich, Andre Knoesen, Erji Mao, and James S. Harris Jr., “In-line fiber evanescent field electrooptic modulators”, Journal of Nonlinear Optical Physics and Materials Vol. 9(1) 79 (2000);        P14) Pochi Yeh, Amnon Yariv, and Chi-Shain Hong, “Electromagnetic propagation in periodic stratified media. I. General theory”, J. Optical Soc. Am., Vol. 67(4) 423 (1977);        P15) Ming Cai, Oskar Painter, and Kerry J. Vahala, “Observation of critical coupling in a fiber taper to a silica-microsphere whispering-gallery mode system”, Physical Review Letters, Vol. 85(1) 74 (2000);        P16) M. Kondow, T. Kitatani, S. Nakatsuka, M. C. Larson, K. Nakahara, Y. Yazawa, M. Okai, and K. Uomi, “GaInNAs: A novel material for long-wavelength semiconductor lasers”, IEEE Journal of Selected Topics in Quantum Electronics, Vol 3(3), 719 (1997);        P17) H. Saito, T. Makimoto, and N. Kobayashi, “MOVPE growth of strained InGaAsN/GaAs quantum wells”, J. Crystal Growth, Vol. 195 416 (1998);        P18) W. G. Bi and C. W. Tu, “Bowing parameter of the band-gap energy of GaNxAs1−y”. Appl. Phys. Lett. Vol. 70(12) 1608 (1997);        P19) H. P. Xin and C. W. Tu, “GaInNAs/GaAs multiple quantum wells grown by gas-source molecular beam epitaxy”, Appl. Phys Lett. Vol. 72(19) 2442 (1998);        P20) B. Koley, F. G. Johnson, O. King, S. S. Saini, and M. Dagenais, “A method of highly efficient hydrolization oxidation of III-V semiconductor lattice matched to indium phosphide”, Appl. Phys. Lett. Vol. 75(9) 1264 (1999);        P21) Z. J. Wang, S. -J. Chua, F. Zhou, W. Wang, and R. H. Wu, “Buried heterostructures InGaAsP/InP strain-compensated multiple quantum well laser with a native-oxidized InAlAs current blocking layer”, Appl. Phys. Lett. Vol 73(26) 3803 (1998);        P22) N. Ohnoki, F. Koyama, and K. Iga, “Superlattice AlAs/AlInAs-oxide current aperture for long wavelength InP-based vertical-cavity surface-emitting laser structure”, Appl. Phys. Lett. Vol. 73(22) 3262 (1998);        P23) N. Ohnoki, F. Koyama, and K. Iga, “Super-lattice AlAs/AlInAs for lateral-oxide current confinement in InP-based lasers”, J. Crystal Growth Vol. 195 603 (1998);        P24) K. D. Choquette, K. M. Geib, C. I. H. Ashby, R. D. Twesten, 0. Blum, H. Q. Hou, D. M. Follstaedt, B. E. Hammons, D. Mathes, and R. Hull, “Advances in selective wet oxidation of AlGaAs alloys”, IEEE Journal of Selected Topics in Quantum Electronics Vol. 3(3) 916(1997);        P25) M. H. MacDougal, P. D. Dapkus, “Wavelength shift of selectively oxidized AlxOy—AlGaAs—GaAs distributed Bragg reflectors”, IEEE Photonics Tech. Lett. Vol. 9(7) 884 (1997);        P26) C. I. H. Ashby, M. M. Bridges, A. A. Alleman, B. E. Hammons, “Origin of the time dependence of wet oxidation of AlGaAs”, Appl. Phys. Lett. Vol. 75(1) 73 (1999);        P27) P. Chavarkar, L. Zhao, S. Keller, A. Fisher, C. Zheng, J. S. Speck, and U. K. Mishra, “Strain relaxation of InxGa1−xAs during lateral oxidation of underlying AlAs layers”, Appl. Phys. Lett. Vol. 75(15) 2253 (1999);        P28) R. L. Naone and L. A. Coldren, “Surface energy model for the thickness dependence of the lateral oxidation of AlAs”, J. Appl. Phys. Vol. 82(5) 2277 (1997);        P29) M. H. MacDougalP. D. Dapkus, A. E. Bond, C. -K. Lin, and J. Geske, “Design and fabrication of VCSEL's with AlxOy-GaAs DBR's”, IEEE Journal of Selected Topics in Quantum Electronics Vol. 3(3) 905 (1997);        P30) E. I. Chen, N. Holonyak, Jr., and M. J. Ries, “Planar disorder- and native-oxide-defined photopumped AlAs—Gas superlattice minidisk lasers”, J. Appl. Phys. Vol. 79(11) 8204 (1996); and        P31) Y. Luo, D. C. Hall, L. Kou, L. Steingart, J. H. Jackson, O. Blum, and H. Hou, “Oxidized AlxGa1−xAs heterostructures planar waveguides”, Appl. Phys. Lett. Vol. 75(20) 3078 (1999).        
Optical fiber and propagation of high-data-rate optical pulse trains therethrough has become the technology of choice for high speed telecommunications. Wavelength division multiplexing (WDM) techniques are now commonly used to independently transmit a plurality of signals over a single optical fiber, independent data streams being carried by optical fields propagating through the optical fiber at a slightly differing optical carrier wavelengths (i.e., signal channels). WDM techniques include dense wavelength division multiplexing (DWDM) schemes, wherein the frequency spacing between adjacent signal channels may range from a few hundred GHz down to a few GHz. A propagating mode of a particular wavelength must be modulated, independently of other propagating wavelengths, in order to carry a signal. A signal carried by a particular wavelength channel must be independently accessible for routing from a particular source to a particular destination. These requirements have previously required complex and difficult-to-manufacture modulating and switching devices requiring extensive active alignment procedures during fabrication/assembly, and as a result are quite expensive. Such devices may require conversion of the optical signals to electronic signals and/or vice versa, which is quite power consuming and inefficient. In various of the patent applications cited above a new approach has been disclosed for controlling optical power transmitted through an optical fiber that relies on the use of resonant circumferential-mode optical resonators, or other optical resonators, for direct optical coupling to a propagating mode of an optical fiber resonant with the optical resonator, thereby enabling wavelength-specific modulation, switching, and routing of optical signals propagating through the optical fiber. A thorough discussion of the features and advantages of such optical power control devices and techniques, as well as methods of fabrication, may be found in these applications, already incorporated by reference herein.
One important element of these latter devices is optical coupling between a fiber-optic waveguide and a circumferential-mode optical resonator. The circumferential-mode optical resonator provides wavelength specificity, since only optical signals substantially resonant with the circumferential-mode optical resonator will be significantly affected by the device. A fiber-optic waveguide for transmitting the optical signal through the control device is typically provided with an transverse-coupling segment, where an evanescent portion of the optical signal extends beyond the waveguide and overlaps a portion of a circumferential optical mode of the circumferential-mode optical resonator, thereby optically coupling the circumferential-mode optical resonator and the fiber-optic waveguide. The transverse-coupling segment may take one of several forms, including an optical fiber taper, D-shaped optical fiber, an optical fiber with a saddle-shaped concavity in the cladding layer, and/or other functionally equivalent configurations. These are discussed in detail in various patent applications cited herein.
The circumferential-mode optical resonator structure may comprise a glass micro-sphere or micro-disk, a fiber-ring resonator, a semiconductor ring/waveguide, or other functionally equivalent structure, described in detail in various earlier-cited applications. A high-Q circumferential-mode optical resonator supports relatively narrow-linewidth resonant circumferential optical modes (i.e., having a linewidth consistent with typical linewidths of a WDM system, TDM system, or other optical data transmission system), which in an optical power control device may optically couple to optical signals of the fiber-optic waveguide of substantially resonant optical wavelength. The circumferential-mode optical resonator therefore provides the wavelength selectivity of the optical power control device. Non-resonant propagating optical signals pass by the circumferential-mode optical resonator relatively undisturbed, and are transmitted through the device. By controllably adjusting the loss per round trip experienced by the circumferential optical mode circulating about the circumferential-mode optical resonator, the optical power control device may function in either of two modes:                1) Switching the circumferential-mode optical resonator between an over-coupled condition (where the loss per round trip in the circumferential-mode optical resonator is small compared to the optical coupling between the fiber-optic waveguide and circumferential-mode optical resonator, and the transmission through the fiber-optic waveguide past the resonator is large) and the condition of critical coupling (at which the optical coupling of the fiber-optic waveguide and circumferential-mode optical resonator is substantially equal to the round trip loss of the circumferential-mode optical resonator, and substantially all of the optical power is dissipated by/from the circumferential-mode optical resonator resulting in near zero optical transmission through the fiber-optic waveguide past the circumferential-mode optical resonator); or        2) Switching states between the condition of critical coupling (near zero transmission through the fiber-optic waveguide) and a condition of under-coupling (where the loss per round trip in the circumferential-mode optical resonator is large compared to the optical coupling between the fiber-optic waveguide and circumferential-mode optical resonator, and the transmission through the fiber-optic waveguide past the circumferential-mode optical resonator is non-zero).        
For each of these modes of operation, there are essentially two classes of mechanism by which one can introduce round trip loss to a circulating optical wave (i.e., resonant circumferential optical mode) in the circumferential-mode resonator. Either optical power of the circulating wave can be absorbed within the resonator, or it can be gated out of the circumferential-mode optical resonator into a second optical component, such as a second waveguide or second resonator. The gating may preferably be achieved by control of the optical coupling between the circumferential-mode optical resonator and the second optical component and functions rather like a trapdoor. These two general possibilities are both disclosed in several earlier-cited applications. The current disclosure describes such devices in greater detail, particularly optical loss components, elements, and/or transducers provided as a separate component to control optical loss from a circumferential-mode resonator by either of these means (as distinguished from designs in which the loss control component is an integral part of the circumferential-mode optical resonator structure).